title: Cleavage of the A alpha-chain of fibrinogen and the alpha-polymer of fibrin by the venom of spitting cobra (Naja nigricollis).
abstract: The effect of Naja nigricollis venom of fibrinogen and highly crosslinked fibrin was examined by SDS-polyacrylamide gel electrophoresis of the reduced products of venom treatment. The venom contains a proteolytic activity which degraded the A alpha-chain of fibrinogen, but had no apparent effect on the B beta- or gamma-chains of the molecule. The venom also readily degraded the alpha-polymer or highly crosslinked fibrin, without apparent cleavage of the beta-chain or the gamma-dimer of fibrin. The venom had no observed effect on plasminogen, indicating that the effects on the A alpha-chain and the alpha-polymer are by direct action of the venom, and not due to activation of plasminogen. The fibrinogenolysis was inhibited by EDTA or 1,10-phenanthroline. Inhibition with EDTA could be reversed by the addition of Zn2+. The fibrinogenolysis was optimal between pH 7 and 8, consistent with the expected pH optimum for a Zn2+ metalloproteinase.
mesh_terms: D000925:Anticoagulants / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004546:Elapid Venoms / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005342:Fibrinolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D010446:Peptide Fragments; D015032:Zinc / Q000494:pharmacology
chemical_list: D000925:Anticoagulants; D004546:Elapid Venoms; D046911:Macromolecular Substances; D010446:Peptide Fragments; D005337:Fibrin; D005340:Fibrinogen; D004492:Edetic Acid; D015032:Zinc